String Theory Seminar
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Mon, 12/10/2009 12:00 |
Marni Sheppeard (Oxford) |
String Theory Seminar  |
L3 |
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Mon, 19/10/2009 12:00 |
Philip Candelas (Oxford) |
String Theory Seminar |
L3 |
| I will discuss a Calabi-Yau manifold which admits free actions by Abelian and non-Abelian groups of order 12. The quotient manifolds have Euler number -6 and Hodge numbers (h^{11}, h^{21}) = (1,4). Apart from the various presentations of the Yau Manifold, that have Hodge numbers (6,9), this is the only other complete intersection CY manifold to admit a free quotient with Euler number -6 and hence three generations of particles with the standard embedding. I will discuss the spectrum of light particles and the possibility of a transgression to a heterotic vacuum on a manifold with Hodge numbers (2,2). | |||
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Mon, 26/10/2009 12:00 |
Joe Conlon (Oxford) |
String Theory Seminar |
L3 |
| Local string models are those where Standard Model degrees of freedom arise on a small region inside a large bulk volume. I study threshold effects on gauge coupling running for such models. The Kaplunovsky-Louis formula for locally supersymmetric gauge theories predicts the unification scale should be the bulk winding mode scale, parametrically large than the string scale where divergences are naively cut off. Analysis of explicit string models on orbifold/orientifold geometries confirms this; the winding mode scale arises from the presence of tadpoles uncancelled in the local model. I briefly discuss phenomenological applications to supersymmetry breaking and gauge coupling unification. | |||
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Mon, 02/11/2009 12:00 |
Jock McOrist (Cambridge) |
String Theory Seminar |
L3 |
| Intersecting brane models in string theory have proven a useful tool for studying the dynamics of quantum field theories. I will describe how certain brane models may be used to shed light on the phenomenon of supersymmetry breaking and vacuum selection in a cosmological context. | |||
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Mon, 09/11/2009 12:00 |
Amihay Hanany (Imperial College) |
String Theory Seminar |
L3 |
| Brane Tilings give a large class of SCFT's in 3+1 and 2+1 dimensions. In this talk I will discuss several attempt to classify all such models. Statistical properties of these models can be derived using some techniques in number theory. | |||
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Mon, 16/11/2009 12:00 |
James Sparks (Oxford) |
String Theory Seminar |
L3 |
| I will introduce a family of supersymmetric Chern-Simons-matter theories in d=2+1 dimensions, labelled by a positive integer n, and argue that these describe the low-energy worldvolume theory of M2-branes at a corresponding family of four-fold hypersurface singularities. There are dual descriptions in Type IIA involving a family of three-fold hypersurface singularities, and also a Type IIB dual of Hanany-Witten type involving D3-branes suspended between 5-branes. The n=1 theory has manifest N=6 superconformal symmetry and is the Aharony-Bergman-Jafferis-Maldacena theory on an M2-brane in flat spacetime. The n>1 theories are not conformal: however, the n>2 theories are all argued to flow to the same superconformal IR fixed point, while the n=2 theory flows to a theory that is AdS/CFT dual to a certain homogeneous Sasaki-Einstein 7-manifold. This is the base of the four-fold "conifold" singularity, and the smooth deformation of this singularity is interpreted as a particular mass deformation in the field theory. The IR theory of this deformation is conjecturally confining. | |||
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Mon, 23/11/2009 12:00 |
Max Banados (Pontificia Universidad Católica de Chile and Oxford) |
String Theory Seminar |
L3 |
| We give a review of several aspects of three dimensional gravity which were discovered long ago but remain active and present in the literature up to today. | |||
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Mon, 30/11/2009 12:00 |
Maximillian Kreuzer (Technische Universitaet Wien) |
String Theory Seminar |
L3 |
| I discuss some theorems and algorithms that we use for enumerating reflexive polytopes and related objects, as well as problems and examples that are of interest in both algebraic geometry and string phenomenology. I would also like to exchange ideas about possible synergies between the numerous current computational activities in the field. | |||
